Mechanical movement



July 20, 1948. vw. L. FITCH MEQHANICL MOVEMENT Filed June 17, 194e s H l L la v 1 4. 3.24..: n? n INVENTOR. WILL/AM L. F/ TCH A TTORNEY Patented July 20, 1948 @unir En #s MECHANICAL MOVEMENT l" liforna ..Appucatiun..unet17,

i iifClams.

. ,.rhieinvennon..relates .toamechanica1-move- .ment,..and..mor.e Vparticularly to .a. mecl1'anical movement-for transmitting motion Lithrougli" the .elbow Vjoint of. an.artificial..armtoL thei hand .or

.ngers thereof.

vPrior I.art .methods .ottransmitting motion from Aa.shoulder..harness to..thehandingers;..or.hook of an articial arm usually involved a stranded 4steel nflexil'ilecable connected .at ,one ,end to the shoulder .harness, .passing through' .the sheath ..and.guides...onthe .external .surface ofthe-upper arm .andthe .'forearm, .andronnectedrat its. other .endto the extremity oftheQlimb. ...ShruggingI-of .the shoulders. caused..the.fharness .-.to..exert.'a .pull .on 'thecable .thus operating .the Vfingers .on-.hook .against .the .action of .-a resilient '.tension.. .element such asaspring .or rubberband. Themechani- .cal actionof,..the systenrwas satisfactory,.but.the

.friction .between the .sheath .andgguides .and .the .sh-irt. .sleeve of. .the wearer, .particularly ,on .the forearm. soon .caused .the sleeve.'to ewear but. .Also the frictionbetween .the cufof the.` sleeve and the cable occasioned by the operating .motion `of thecable soon. caused .Wearonthecuffi Fur- .therrnore,..the sheath rand..guides..caused. an un- .,.natural .bulge inthe` contour of the. sleeve.

Objects of .the-present' invention...therefore-are to provide. a mechanical` movement or.linkage.-for

vtransmitting -motion 'from 1a .shoulderf-harnessfto the extremity oran-artificialrlimbvWhich-iwill not Wear the sleeve of thetarnpute'eg to provide amechanical movement of theztype= described which vwill be almost entirely Vbeneath.the surfacer of the Harm -andsubstantially enclosed within aA-hollow elbow jointxand lorearrn;-y and. tov provide af mechanical movementfaof thetype,describedfwhich .will be easytoconstruct and-f-simpleiand-:durfable design.

In accomplishing these and'ntherobjectszofrthe present invention,.fs1;have providerimproveddetails of structure; therpreferred form-'ofiwhich is illustrated in the accompanying drawings, Wherein:

Fig. 1 is alongitudinal.crossesectional View on an anterior-posterior plane of a parti-ally flexed prosthetic arm for anabove-the-elbow amputation embodying the features ofthe :present invention;

Fig. .2 is a cross-sectionalyiew of the elbowlo'f .the'arm of Fig. l in extendedposition .takenalong amedial-lateralmid-plane; A v

"Fig 3 is a cross-sectional view taken along the line 3-3 of Fig. 2; and

Fig. 4 is a partial cross-section of the pulley Referring more `particularly 'fto'4v `thel fdrawing, l'numeral `I indicates generally Athe upper armY seg- Y 45 Nrnentof a prosthesis having fa lowerfor elbow-portion l2 Ymade of Wood,v aluminum, v#orf other `suitable `material 4and =-a-fcovering 3 of '-lleather or #the like: extended toward the shoulder tofornr` a' vconventional bucket for receiving `the `stump fthe 10 nainputatedarm. Thedistal' end'of the upperarm is hcllovved out as at 4; to formlthe generally 'sphericalfsocket of a-`ball and socket `'elbevvifjo'int.

A hollow forearm, generallvindicated*at-5;'in cludes a distal segment..made of metal, plastic,

115 laminated fabric or the like and is provided with 1an"elbow"segment A'l *joined to the `distalseg-ment as at f8, bylscrevvs or other *means'notlshown .The elbow 'segment hasafgenerally 'spherical' por- ."ti'cn 9 forming the ball'fofthe `ball`and-socket joint. The ball Slisv pivotedto -thesocketcmem- 'berfby means 'such as a cylindrical 'pi'n ITU- passing .-through"openingsdnstrips off-metal Il `andiflz fastened to'oppositesides of the-upperarm member 2.' The^pin `is non-'rotatably keyed La's-"a-td 3 to`the strip' l2^by means "suchas corresponding ats'formed onthe Aend 'ofpn lll-andiinthe opening inf stripl 2. {The pin I Il isA prevented from axial` displacement by' the r`retainingscrew 'i I4.

vThe balli'and forearm turnifreelyonthe pin by v virtue ofthe'cylindricalopenings IBin-thewv'all of the bau.

As the distal end of the forearm a limb `extremity such as a. hand, ngers,' orhook'isattached TIn the embodimentfillustrated'thisfe'xtreniity is illustrated as aknovvn'typfeofhook I Shaving a relatively xednger Il and amovablenger l iB pivoted to the xediinger at l9.' The 'fingers are'held inclcse'd positionv by one .or more rubber bands'. "The'ngers are opened'infaS-known 4.0rnanner by. pulling .on a cablellA xedas at 22 [9 ".The noveLm'echanism .forA transmitting.. Ino- .tionfromasholderfharness to .theicableZjl .will

...now bedescribed.

Slidably and' rotatably .mounted .onthelpin l0 A.is a'- oylindri-cal .rack..23 .having,a .plurality of...an y .nular .rack Y.teeth .24. Closely ...surrounding .the

-.rack;.23.are.a pair.ofvsleev.es I25...and`l.26. .The .f -.sleeve. 2.5.. is lxed..relati ve to. the. forearm ..=5 .by V.virturehftbeing'fastened,1as.byscrews 21,-,to..the.ba11

I9. l'lhe. sleeve 25 .is ,provided.-vvith.` a. bearingt pro- .,jection ,23, brazed-or .Welded theretooasat .-29. The projection 28 serves as a bearing support for a shaft 30 having a pinion 3| fixed thereon, in

meshing engagement with the rack 23. The projection 28 also serves as a housing for the pinion 3|. A grooved wheel 32 is also xed to the shaft 30 as by means of a pin 33. The cable 2| has one of its ends connected to the wheel 32 by means of a bead 34, Fig. 4, fixed thereto and retained in an opening 35 -communicating with the groove of the wheel through a bore 36. Th'e cable 2| is prevented from accidental displacement olf the groovedV wheel by a circumferentially extending guard 31, fixed to or formed on the sleeve 25. The cable 2| passes off the wheel through guide means such as a cable sheath 38 and a cable sheath' anchor 39 fixed to the inside of the forearm and thence through an opening 4|] at; the distal end of the forearm to terminate, as aforedescribed, at 22.

The sleeve 26, similar to sleeve 25, is fixed relative to the upper arm member I by virtue of the fact that it is fixed, as by a pin 4|, to the pivot pin l0 which, in turn is xed relative to the upper arm member. A bearing projection 42, pinion 43, pinion shaft 44, grooved wheel 45 and cable guard 46 are provided for the sleeve 26 similar to those on sleeve 25. A cable 41 is fixed to the wheel 45 and extends through a circumferential slot 48 in the hollow ball 9, thence through a bore 49 directed generally supra-laterally in the portion 2 of the upper arm. The cable is surrounded in the bore by a iiexible sheath 50. The sheath and cable emerge superiicially on the proximal portion of the upper arm and there the end, not shown, of cable is fastened to the shoulder harness in a known manner.

Operation In using the prosthesis of the present invention the shoulders are shugged causing a tension to be exerted on the cable 41. This causes the wheel 45 to rotate turning the shaft 44 and pinion 43 clockwise as seen in Fig. 2. This causes the rack 23 to move to the left in Fig, 2 rotating the pinion 3|, shaft 30, and wheel 32 counter-clockwise in Fig. 2. Counter-clockwise motion of wheel 32 applies tension to the cable 2l which pulls the finger I8 to open the hook against the force of the rubber bands 20. harness allows the bands 20 to close the hook, reversing the movement of all the parts.

`If the forearm is flexed or extended no disturbance of the linger operating mechanism occurs since the teeth of the pinions 3| and 43 are free to ride around the annular grooves between the teeth of the rack 23.

While I have shown but one embodiment of my invention, it is apparent that the device is susceptible to modification Without departing from the spirit of the invention. I do not wish, therefore, to be limited by the disclosures set forth, but only by the scope of the appended claims.

I claim:

1. In an artificial arm having a shoulder harness, a hollow ball and socket elbow joint, and a finger hook, a cylindrical rack disposed within said hollow ball with its axis coincident with the elbow axis and slidable along its axis, a sleeve on said rack iixed to rotate with the socket member of said joint and having a transversely extending bearing projection, a pinion meshing with said rack and journalled for rotation in said projection, a grooved wheel fixed to rotate with said pinion, a flexible tension element passing through an opening in the wall of said ball and lying around said wheel to coact therewith at Releasing the shoulder the periphery thereof, a second sleeve fixed to rotate with said ball and having a second transversely extending bearing projection, a second pinion meshing with said rack and journalled for rotation in said second projection, a second grooved wheel fixed to rotate with said second pinion and a second flexible tension element lying around said second wheel and coacting therewith at the periphery thereof, one of said flexible elements being connected to said harness and the other of said iiexible elements being connected to said finger hook.

2. In an artificial arm having a shoulder harness, a hollow ball and socket elbow joint, and a finger hook, acylindrical rack disposed within said ball with its axis coincident with the elbow axis and slidable along its axis, a bearing support fixed relative to said ball, a pinion journalled in said bearing support and meshing with said rack, a flexible tension element in torque-reacting relationship to saidpinion, a second bearing support xed relative to said socket, a second pinion journalled in said second support and meshing with said rack and a second iiexible tension element in torque-reacting relationship with said second pinion, one of said elements being connected to said shoulder harness and the other of'said elements being connected to said finger hook.

3. A mechanical movement for transmitting motion through a joint pivotally connecting two members comprising a cylindrical rack mounted for slidable movement along its axis and having its axis coincident with the pivot axis of the joint, a bearing support fixed relative to one of said members, a pinion journalled in said support and meshing with said rack, a iiexible tension element in torque-reacting relation with said pinion, a second bearing support xed relative to the other of said members, a second pinion journalled in said second support and meshing with said rack, and a second. flexible tension element in torque-reacting relation with said second pinion.'

4. In an artificial arm having an upper arm, a forearm articulated to said upper arm at an elbow joint, and a finger member, mechanism for transmitting actuating motion to said linger member through said elbow joint independently of articulatory motion 4of said joint comprising a cylindrical rack mounted for sliding motion along its axis and having its axis coincident with the axis of said elbow joint, a bearing support xed relative to said upper arm, a pinion journalled in said support in meshing engagement with said rack, a iiexible tension element for exerting a torque on said pinion, a second bearing support fixed relative to said forearm, a second pinion journalled in said second support in meshing engagement with said rack, and a second flexible tension element for transmitting actuating motion of said second pinion to said finger member.

WILLIAM L. FITCH.

REFERENCES CITED The following references are oi record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,026,459 Caretta Dec, 31, 1935 2,273,602 Trant u f Feb. 17, 1942 

